The invention relates to a plasmid-free clone of E. coli strain DSM 6601, a method of its preparation and the use of the bacteria obtained in this manner as a cloning vehicle.
E. coli, a bacteria that occurs in nature, especially in the intestines of humans and animals, has long been the subject of intensive microbiological and genetic engineering research and is used in genetic engineering in particular for cloning and/or expressing certain genes and/or proteins.
Most strains of the genus Escherichia are pathogenic outside of the lumen of the bowels and generally cause infections at the affected sites. A non-pathogenic strain of the genus Escherichia coli is the strain DSM 6601 deposited in the German Collection for Microorganisms, that deviates in a few genetic features from all other E. coli strains. However, it turned out that this strain can be manipulated genetically only under difficult circumstances and partially not at all and therefore cannot be used as a simple cloning means.
E. coli DSM 6601 naturally contains two plasmids designated as pMut1 or pMut2 that have a size of 3177 and 5552 kb. These plasmids and their DNA sequences are described, e.g., in U.S. Pat. No. 6,391,631.
The Escherichia coli strain having accession number DSM 6601 was deposited under the terms of the Budapest Treaty on Jul. 11, 1991 in the German Collection for Microorganisms, DSMZ-Deutsche Sammlung von Mikrooganismen and Zellkulturen GmbH, located at Mascheroder Weg 1b, D-38124, Braunschweig, Germany.